In some scanning imaging systems such as scanning mammography systems, the object to be imaged is scanned by movement of the imaging system's detector. Some of these scanning imaging systems include an interferometer arrangement that allows grating based phase contrast or dark-field imaging. See for instance C. Kottler et al, “Grating interferometer based scanning setup for hard x-ray phase contrast imaging”, Rev. Sci. Instrum. 78, 043710 (2007).
The proposition in phase contrast imaging is that radiation intensity as detected at the detector does not only encode information on attenuation (traditional x-ray radiography is based on this) but also holds information on refraction as well as small angle scattering (related to the so-called dark-field image) experienced by the radiation in its passage through the object to be imaged.
Scanning based phase contrast or dark-field imaging is complicated by the fact, that due to the scanning motion, image information redundancy is introduced. The image information on phase contrast or dark-field contrast is “spread out” across a plurality of pixels. Also, it has been observed that phase contrast and dark-field imagery occasionally suffer from artifacts.